This invention generally relates to a pump and valve assembly for inflating a prosthesis. More particularly, the invention relates to pressure-based mechanisms that inhibit spontaneous inflation of the prosthesis, including stiffening and support mechanisms that also improve the function of the valve.
One common treatment for male erectile dysfunction is the implantation of a penile prosthesis. Such a prosthesis typically includes a pair of inflatable cylinders, which are fluidly connected to a reservoir (typically liquid filled) via a pump and valve assembly. The two cylinders are normally implanted into the corpus cavernosae of the patient and the reservoir is typically implanted into the patient""s abdomen. The pump assembly is implanted in the scrotum.
During use, the patient actuates the pump and fluid is transferred from the reservoir through the pump and into the cylinders. This results in the inflation of the cylinders and thereby produces the desired penis rigidity for a normal erection. Then, when the patient desires to deflate the cylinders, a valve assembly within the pump is actuated in a manner such that the fluid in the cylinders is released back into the reservoir. This deflation then returns the penis to a flaccid state.
Presently, the pump and valve assembly used in such implantable prostheses share certain similar characteristics. For example, they include fluid pathways allowing the flow of fluid to and from the reservoir, as well as to and from the cylinders. This fluid flow is controlled by one or more check valves positioned in the fluid pathways within the housing of the assembly.
A compressible pump bulb is also attached to the housing and is in fluid communication with the various fluid pathways therethrough. In order to inflate the cylinders, the compressible pump bulb is actuated by the patient, thereby urging fluid past the check valves into the cylinders. In order to deflate the cylinders, the valve housing is grasped and squeezed (through the patient""s tissue), causing the various check valves to unseat and allow fluid to flow back to the reservoir.
Since the pump and valve assembly is positioned within the patient""s scrotum, the various components of the assembly must be small. As a result, manipulation of the pump and valve assembly is sometimes difficult. For example, patients requiring the use of penile prosthesis discussed herein are oftentimes elderly and have a reduced dexterity as a result of aging. Thus, in some instances, even locating the device within the tissue can be a challenge, let alone identifying the correct portion of the assembly to actuate. More specifically, with some patients, it may be difficult to determine whether the housing portion of the assembly that leads to release or deflation of the cylinders is being grasped or whether the bulb portion which would be used to inflate the cylinders is being grasped.
Notably, the length of the valve assembly is determined (at least in one direction) by the size of the various check valves and the distance such valves must move in order to open and close the various fluid passageways. As a result, such a pump and valve assembly typically is longer in a direction parallel with the check valves. Moreover, in order to release the check valves in an assembly configured in this manner, the patient must grasp the narrower, shorter side walls of the assembly and compress them together. Since such a configuration can present challenges insofar as the spring tension of the check valves at the time of desired deflation is typically at a maximum while the surface area of the assembly which must be compressed in order to cause such deflation is at a minimum. This condition can lead to a situation where the patient has difficulty actually compressing the assembly, or in extreme circumstances, actually loses grip of the assembly during such attempts at deflation.
Although the existing devices function with extreme efficiency and reliability, for some patients it appears there is a desire for a pump and valve assembly in an implantable prosthesis that improves operative manipulation of the assembly. One such prosthesis pump is disclosed in co-pending U.S. patent application Ser. No. 09/749,075, entitled xe2x80x9cPenile Pump With Side Release Mechanism,xe2x80x9d which is assigned to the Assignee of the present invention and is incorporated herein by reference. However, the operational efficiency of the prosthesis pump could be further improved by optimizing the function of the check valves.
Metal on metal contact can cause undesired wear of components over time. This can affect the performance of any product. In the pump and valve assembly, the check valve and spring engage one another at an end of the check valve to inhibit movement. Typically, at least a portion of the check valve and spring are made of a metal material such as stainless steel. The repeated application of a spring force by the spring onto the end of the check valve tends to wear or degrade the contact portions of the check valve and spring. This metal on metal contact over time negatively impacts the performance of the valve assembly.
The orientation of the pump and valve assembly creates a condition where the spring applies a force in both the axial and sideways directions onto the check valve, during actuation of the prosthesis pump. The axial force acts to move the check valve poppet into the valve assembly, while the side force has the unintended consequence of pushing the check valve sideways causing the valve to tip sideways. When the check valve is pushed sideways into the valve housing, the valve housing deforms which causes the check valve to be misaligned. This results in the check valve being restrained from moving axially into the valve housing to reach its open position.
Finally, the repeated exertion of axial and side forces of the spring on the end of the check valve tends to cause a reduction in the stiffness of the of the spring. Specifically, the spring is a thin elongate member having a bent portion. As a patient grasps the narrower, shorter side walls of the assembly and compresses them together, the spring flexes inwardly to force, via axial and side forces, the check valve to move to an open position. When the patient releases the side walls of the assembly the spring returns to its original position, permitting the check valve to return to a closed position. The repeated flexing of the spring may cause a reduction in stiffness of the spring, particularly at the bend. This reduction in stiffness may lead to the spring deflecting during actuation in an unintended manner, which can permanently deform the spring. Permanent deformation of the spring has the undesired effect of inhibiting the full axial travel of the check valve between the open and closed positions.
There exists a need to provide a prosthetic penile implant that reduces the wear of the contact point of the check valve and the spring. There is a desire to improve the function of the valve assembly by prevention of deformation of the valve housing and misalignment of the check valve. There is a need to provide a barrier to sideways movement of the check valve when moving between the open and closed positions. Additionally, there is a desire to increase the strength and stiffness of the spring to prevent the spring from deflecting during actuation and prevent permanent deformation of the spring.
The present invention provides various features which taken alone or in combination with one another provide for an improved pump and valve assembly for an implantable prosthesis. The present pump and valve assembly includes a pump bulb that must be differentiated from the valve housing when inflation of the cylinders is desired. The pump bulb itself has dimensions that are somewhat different than the remainder of the housing. However, to supplement differentiation between the bulb and the valve housing, the valve housing is provided with a textured surface so that even through tissue the patient is able to readily discern which area comprises the pump bulb and which area comprises the valve housing. This is important in that the pump bulb is compressed for inflation while the valve housing is compressed for deflation.
The pump assembly of the present invention is also configured such that it has a length longer than its width, with its internal check valves running parallel with the length. To release fluid from the inflated cylinders, the internal check valves are actuated so that they move in a direction parallel to the length, until they open. To achieve this action directly, the opposing sides of the width of the valve housing are compressed. This compression causes actuation of the internal check valves.
In addition, an actuating bar is positioned within the valve housing parallel with and extending along at least one of the sides of the length. An arm attached to the actuating bar extends along a portion of one of the sides of the width in close proximity to the tip of one of the check valves. Thus, the configuration of the actuating bar causes it to engage and open the check valve allowing fluid to flow from the cylinder to the reservoir. Furthermore, the patient can grasp the valve housing in virtually any orientation and when pressure is applied, the actuating bar will act either directly or indirectly to open the appropriate check valves. Thus, so long as the patient grasps any portion of the pump and valve assembly other than the pump bulb, compression will result in the desired opening of the check valves which will allow the cylinders to deflate.
Furthermore, since the patient can grasp the valve housing along the sides of the length, i.e., surfaces with larger surface area, less pressure need be applied to achieve the successful opening of the check valves. In other words, by increasing the surface area that is engaged by the patient""s fingers and appropriately positioning the actuating bar, less force need be exerted by the patient to achieve the desired result.
The textured surface of the valve housing not only helps the patient identify the correct portion of the pump and valve assembly to actuate, it also serves to prevent slippage once the patient begins to compress the housing. Thus, what is achieved is an efficient and ergonomic pump and valve assembly for an implantable prosthesis. The pump and valve assembly can advantageously be formed from a minimal number of components. That is, all that need be molded are a valve block and a corresponding pump bulb which surrounds the valve block. The various check valves can be inserted into the valve block and then placed within the interior of the pump bulb, thus forming a completed assembly. This results in certain manufacturing efficiencies, thus reducing both cost and time of production.
To further improve the operational efficiency of the pump and valve assembly, the check valve is made of a metal material with a plastic member disposed over a segment of the metal material. The plastic segment of the check valve prevents undesired frictional metal on metal contact with the actuating bar, and prevents premature wearing of the contact point of the two components.
To further improve the life of the valve assembly, ribs, that extend across a bend, are added to the actuating bar. This modification increases the strength and stiffness of the spring and prevents the actuating arm from deflecting during actuation. In turn, full axial travel of the check valve is ensured. Increasing the strength of the bend also prevents permanent deformation of the spring when normal deflection occurs during actuation of the valve assembly. Another rib is disposed along the actuation face of the actuating bar to limit deformation of the actuation face during actuation of the valve assembly.
To improve the ease of deflation, a stiff poppet support wraps around the valve body and rests against a portion of the check valve. The poppet support has a shelf that provides smooth surface for a portion of the check valve to slide along. The poppet support contacts the check valve and prevents undesirable sideways movement of the check valve against the valve body. The positioning and configuration of the poppet support thus allows the check valve to easily move axially into the valve body to an open position. This results in improved operational efficiency of the check valve and an extended operating life.